Electrical inductance and method



March 12, 1968 c, RECHEL ELECTRICAL INDUGTANCE AND METHOD Filed June 7, 1967 United States Patent 3,3735% ELECTRICAL INDUCTANCE AND METHOD Edwin C. Rachel, Lancaster Road, Shirley, Mass, 01464 Continuation-impart of application Ser. No. 592,615,

Nov. 7, 1966. This application June 7, 1967, Ser.

9 Claims. (Cl. 336-192) .ABSTRACT OF THE DISCLQSURE An electrical inductance and method. The inductance includes a coil of relatively fine wire wound on a coil form and a flexible wrapper. The wrapper carries contact means adjacent one edge thereof from which a lead wire of relatively large diameter extends. Said wrapper edge is positioned between the last turn of the coil winding and the remainder of the winding and the last turn is secured to the contact means. The wrapper extends circumferentially about the outer surface of the coil.

Related application This application is a continuation-in-part of my copending application entitled wrapper for Inductive Winding and Method, Ser. No. 592,615, filed Nov. 7, 1966, now abandoned.

Background of the invention This invention relates to an electrical inductance and method, and, more particularly, to means for constructing inductances such as high-voltage windings.

The invention finds particular utility in connection with automobile ignition transformers wherein the secondary windings develop voltages of the order of l5,000-20,000 volts. For this purpose, relatively fine wire, i.e., lighter than No. 38 AWG is wound in thousands of turns and there is a problem of making a connection to this relatively fine wireparticularly the external lead. In the past, these inductances have been gang wound to provide to inductances at a given time. This is done on a stick which is rotated at relatively high speed by a mandrel or arbor. As the last turn is completed, a length of tape is laid along the length of the stick to secure the last turns and the stick is then transversely severed to make a plurality of inductances. The physical connection is made by handproduction-line workers first twisting the very fine wire ending about a braided lead. Thereafter, a saddle consisting of a relatively thick layer of durable insulating material is laid down on the inductance to protect the same against penetration of any spurs which might result from the soldering operation wherein the fine wire is secured to the braided wire. After this, the entire assembly is overwrapped with a length of insulating material. It will be appreciated that the foregoing operation is not only time-consuming, but by virtue of the various manipulating operations may tend to destroy the precise character of the inductance.

Summary of the invention The invention avoids the time-consuming and potentially damaging procedures discussed. The wrapper facilitates connecting the fine wire of the coil to the heavy external lead which is used to connect the inductance to a circuit. The wrapper also provides an insulating cover for the coil and protection against spurs resulting from soldering or otherwise connecting the fine wire to the lead wire.

Description of the drawing FIG. 1 is a fragmentary perspective view of a stick being gang-wound and wherein the inventive wrapper is about to be installed thereon;

FIG. 2 is a perspective view, partially broken away, of a completed inductance featuring the invention;

FIG. 3 is a fragmentary perspective view of a modified form of a wrapper in which the contact means is applied by a clinching or stapling operation;

FIG. 3A is a perspective View of the contact means in its unclinched configuration prior to installation in the form seen in FIG. 3; and

FIG. 4 is a fragmentary exploded view of yet another form of a wrapper embodying the inventive concept.

Description of the preferred embodiment In the illustration given, and with reference to FIG. 1, the numeral -19 designates generally a stick which is in the process of being gang-wound to provide a plurality of windings 10a, 10b, etc. The stick 10 includes a tube 11 which advantageously may be constructed of spirallywound insulating material, i.e., a coil form, and overlaying the tube 11 are numerous turns of fine wire 12. The fine wire 12 is provided by various wires as at 13, 13a, 13b, etc., emanating from reels (not shown) in conventional fashion. In the illustration given in FIG. 1, the winding operation is concluded and the stick 10 is no longer rotating in the direction of the arrow 14 (see the extreme lefthand portion of FIG. 1). At this juncture, a wrapper generally designated 15 is about to be installed on the stick 10.

The wrapper 15 is seen to include a generally rectangular sheet 15a of fibrous material such as kraft paper and has adhesively-installed at spaced intervals along its length contact means as at 16. It will be appreciated that the contact means 16 may be a continuous strip coextensive in length with the sheet 15a. Each contact means has anchored thereto as by welding, a braided wire or external finishing lead 17. The free ends of the braided leads 17 may be advantageously secured by a longitudinally-extending length of adhesive tape as at 18. The finishing lead 17 may also be a fiat strip of conductive material and may be formed integrally with the contact means.

In the practice of the invention, the wrapper 15 is advanced in the direction of the arrow 19 (see the central portion of FIG. 1) and thus fits or is lodged between the various wires or final turns 13, 13a, 13b and the bulk of the stick 10. As the stick It) continues to rotate, the wrapper is rolled around the stick 10 to result in a configuration such as is seen in FIG. 2. Prior to the enveloping operation, each lead 13, 13a, etc., is secured to its associated contact means as at 16, 16a, 16b, etc., as by soldering-this being depicted by the enlarged portion 20 about the fine wire 13 in FIG. 2. The wrapper 15 is adhesively secured in place on the stick 10 to provide the configuration seen in FIG. 2 and this may be done either by applying adhesive to the stick 10 per se or by equipping the underside of the wrapper 15 with the adhesive or by pressure-sensitive tape.

In the illustration given in FIGS. 1 and 2, the contact means 16, 16a, etc., which are constructed of electricallyconductive material (in contrast to the electrically-insulating character of the sheet 15a constituting the bulk (It; tlae wrapper 15, are adhcsively secured to the sheet An alternative way of securing the contact means is seen in FIGS. 3 and 3A. In FIG. 3 the numeral designates generally the wrapper which is again a sheet 115a of insulating material such as kraft paper and the contact means 116 is seen to include depending lugs as at 121 which are adapted to be clinched after being inserted through previously-provided slits 122 in the wrapper 15, thereby providing a finished wrapper unit.

With heavier contacts 116 it may be possible to achieve a penetration by sufficiently heavy tangs or prongs, thus eliminating the need for previously-provided slits.

Still another embodiment of the invention is seen in FIG. 4 wherein the wrapper is generally designated by the numeral 215 and is seen to include contact means as at 216 which is a strip extending the length of the wrapper 215. At spaced intervals the wrapper sheet 215a is apertured as at 222 so as to expose the conductive contact means 216. The contact means 216 is mounted in place on the underside of the wrapper 215 by an adhesive strip as at 223 which has a width somewhat greater than the contact means 216.

It will be seen that the invention permits high-speed automatic finishing of coils, particularly those utilizing many turns of fine wire. The winding operation is already automated and no longer is it necessary to hand-manipulate the various inductances to achieve the final form as seen in FIG. 2.

The wrapper 15 can be automatically, i.e., mechanically, inserted in position between the lead wires 13, 13a, 13b, etc., and the main body of the wound stick, i.e., the almost complete windings a, 1%, etc. Inasmuch as the contact means 16, 16a, 16]), etc., are in alignment with the various lead wires 13, 13a, 13b, the further rotation of the stick 10 brings the lead wires 13, 130, etc., into engagement with the contact means 16, 16a, etc., whereupon a machine-soldering operation is easily performed. Completion of the rotation of the stick 10 causes the enveloping of the stick with the wrapper 15 and at this stage, the entire stick still exists as a unit, ready for transverse severing with the braided leads ready for connection to an electrical component or the likethat is, the unit or component deriving current form the inductance. In some instances, the wrapper may be used as an insulation means between the secondary and primary of the transformer and where the two sections of the transformer are Wound consecutively on the same mandrel, the Wrapper may be employed as a means for inter-connecting the secondary and primary windings when the same are to be connected to ground.

In the illustration given, I utilize as the sheet 15a of the wrapper 15, a kraft paper having a thickness of the order of 0.005" to about 0.010". Other advantageous materials of construction include varnished linen, laminates of Mylar (ethylene terephthalate, etc.). The contact or connection means provided in the form of the contacts 16, 16a, etc., are advantageously tin-plated copper having a thickness of the order of about 0.003" which is commercially available. In certain instances, plain, uncoated copper may be utilized, the object being to provide solderable material of construction. The braided leads 17 advantageously extend outwardly of the bulk of the many turns 12 and can in certain instances extend at a slight angle to the plane of the ends of the coil C (see FIG. 2). This then provides the braided leads 17 in readily-accessible position after the previously-mentioned transverse severing operation is performed. I prefer to anchor the braided leads 17 to the contact means 16 by welding since then the subsequent soldering operation does not affect the previously-established connection.

While in the foregoing specification a detailed description of an embodiment of the invention has been set down for the purpose of illustration, many variations in the details hereingiven may be made by those skilled in the art without departing from the spirit and scope of the invention.

I claim:

1. An electrical inductance comprising a coil form, a winding on said coil form, said winding being provided by a plurality of turns of an electrical conductor, a wrapper of flexible material having electrical insulating properties covering said winding, one edge of said wrapper being interposed between the last turn of said winding and the remainder of the winding, contact means of electrical conductive material mounted on said wrapper adjacent to but spaced from said edge, said last turn extending over the outer surface of said wrapper and secured to said contact means, lead wire means operatively associated with said contact means and adapted to be connected to an electrical component, and removable hold down means temporarily securing the other end of said lead wire means to said sheet.

2. The electrical inductance of claim 1 in which said contact means comprises a plate clinchingly secured to said wrapper.

3. The electrical inductance of claim 1 in which said lead wire extends at a slight angle to the direction of said winding turns to facilitate axial access.

4. An electrical inductance comprising a coil form, a plurality of axially spaced windings on said coil form, each of said windings being provided by a plurality of turns of an electrical conductor, a wrapper of flexible material having electrical insulating properties covering said windings, one edge of said wrapper being interposed between the last turn of each of said winding and the remainder of the windings, contact means of electrical conductive material mounted on said wrapper adjacent to but spaced from said edge, said last turns extending over the outer surface of said wrapper in a direction generally parallel to a plane normal to the axis of said coil form and being secured to said contact means, and lead wire means for each of said windings, each of said lead wire means projecting away from said contact means, said lead wire means having a thickness greater than the thickness of said last turns.

5. The electrical inductance of claim 4 in which said contact means comprises a plurality of longitudinally spaced plates clinchingly secured to said wrapper.

6. The electrical inductance of claim 4 in which said contact means comprises an elongated strip extending generally parallel to said one edge.

7. A method of constructing an inductive Winding comprising the steps of winding a plurality of turns of fine wire on a coil form, inserting a wrapper sheet between the wound form and the last length of wire thereto, said wrapper being equipped with a contact in alignment with said lead wire, connecting said lead wire to said contact and wrapping said wound form with said wrapper.

8. The method of claim 7 in which said lead wire is of lighter gauge than about No. 38 AWG.

9. The method of claim 7 in which a plurality of inductances are simultaneously provided during said winding, said wrapper being equipped with contact means for each lead Wire of said plurality of inductances.

References Cited UNITED STATES PATENTS 1,836,948 12/1931 Anderson 336--208 2,125,431 8/1938 Dinion 336192 LEWIS H. MYERS, Primary Examiner.

E. GOLDBERG, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2x373 3 Dated March 12, 1968 Inven flx) Edwin C. Rechel It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the Claims:

Column 4, Lines 51, 53 and 58, each occurrence,

the word "lead" should read --f1ne--.

Signed and sealed this 16th day of November 1 971 (SEAL) Attost:

EDWARD M.FI.ETCHER,JR. ROBERT GOTTSCHALK Acting Commissioner of Patents Attesting Officer nu "A earn II 

